The principal goal of the Population Studies Center is to increase the quantity and improve the quality of population research conducted at Penn. To do this, it provides a setting, within the School of Arts and Sciences, for the interchange of information about current research and research opportunities; core facilities on which individuals can rely for assistance in conducting research; an institutional structure that can represent the interests of population researchers in discussions about the allocation of resources within the University as well as extramurally; and a program intended to attract visitors with special knowledge of techniques, data, and research findings that can enhance the capabilities of Center researchers and suggest new directions for research. The PSC is associated with a strong training program for pre- doctoral students and postdoctoral fellows who frequently act as junior colleagues. This application requests continuation of the P30 Center Core Grant that provides most of the support for the core facilities cited above. The three cores are Administrative, Computer and Library. Over the last five years, the program of funded research has more than doubled. The Cores now support the competitively awarded grants of 35 research associates. We therefore request continuation of these three cores with increased personnel resources. The greatest increase requested is for the Computer Core, so that PSC researchers can have access to a greatly improved computing environment that will enhance their productivity.